// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System;
using Microsoft.AspNetCore.Localization;

namespace Microsoft.AspNetCore.Builder;

/// <summary>
/// Extension methods for the <see cref="RequestLocalizationOptions"/>.
/// </summary>
public static class RequestLocalizationOptionsExtensions
{
    /// <summary>
    /// Adds a new <see cref="RequestCultureProvider"/> to the <see cref="RequestLocalizationOptions.RequestCultureProviders"/>.
    /// </summary>
    /// <param name="requestLocalizationOptions">The cultures to be added.</param>
    /// <param name="requestCultureProvider">The cultures to be added.</param>
    /// <returns>The <see cref="RequestLocalizationOptions"/>.</returns>
    /// <remarks>This method ensures that <paramref name="requestCultureProvider"/> has priority over other <see cref="RequestCultureProvider"/> instances in <see cref="RequestLocalizationOptions.RequestCultureProviders"/>.</remarks>
    public static RequestLocalizationOptions AddInitialRequestCultureProvider(
        this RequestLocalizationOptions requestLocalizationOptions,
        RequestCultureProvider requestCultureProvider)
    {
        if (requestLocalizationOptions == null)
        {
            throw new ArgumentNullException(nameof(requestLocalizationOptions));
        }

        if (requestCultureProvider == null)
        {
            throw new ArgumentNullException(nameof(requestCultureProvider));
        }

        requestLocalizationOptions.RequestCultureProviders.Insert(0, requestCultureProvider);

        return requestLocalizationOptions;
    }
}
